A 30-year-old woman was allegedly sexually assaulted by an unknown man in Reservoir, in Melbourne's north, in the early hours of December 4 last year.
She was dropped off on the nature strip outside her house by a rideshare driver at about 2am before she lost consciousness, police say.
Police allege the woman woke up sometime before 4am in an unknown nearby unit to find a man sexually assaulting her.
She managed to push off the man and leave, calling police when she arrived home.
How the woman was moved from the nature strip to the unit where the alleged assault occurred is one of the factors under investigation.
Police said the unit is unoccupied by permanent residents but is used by squatters and "multiple unknown people".
They also said the rideshare driver who dropped the woman near her home has been ruled out as a suspect.
The alleged victim, who cannot be identified for legal reasons, is expected to front the media with a senior officer to make a public appeal for information later today.
In an effort to prompt some more information from the public, police have released a computer-generated image of a man who may be able to assist them.
"The man is perceived to be of Middle Eastern appearance, aged between 50- and 60-years-old, with dark hair, olive skin, a thin build, and clean shaven," Victoria Police said in a statement.
Anyone who can help identify the man or who has dashcam or CCTV footage of the area on the night in question is urged to contact Crime Stoppers.
20°C